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Comment by lmilcin | Hacker News Reader

Actually, nuclear fallout is present in everything.

Following Trinity test and the rest of nuclear testing campaign, every single living thing or any matter that has been processed in any way has been contaminated and shows high background radiation (compared to pre-Trinity test).

That's why some materials like steel from ships comissioned before Trinity test or lead ballast from sunken Roman ships is highly sought after where low background radiation material is required.

https://www.theatlantic.com/science/archive/2019/10/search-d...

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For lead the radioactivity comes from uranium mixed with the original ore, not from outside sources. That's why it needs to be hundreds or thousands of years old rather than just pre 1945.

>All lead mined on Earth naturally contains some amount of the radioactive element uranium 235, which decays, over time, into another radioactive element, a version of lead called lead 210. When lead ore is first processed, it is purified and most of the uranium is removed. Whatever lead 210 is already present begins to break down, with half of it decaying on average every 22 years. In Roman lead almost all of the lead 210 has already decayed, whereas in lead mined today, it is just beginning to decay.

https://www.scientificamerican.com/article/ancient-roman-lea...

Probably a stupid question, but wouldn’t all lead have started decaying at the same time? Why would lead only start to decay once it has been mined?

Only lead 210 is radioactive. Lead 210 is only created by uranium.

Lead 210 has a short half-life, uranium 235 has a long one. Thus, once uranium is removed, lead 210 levels drop "quickly".

"When lead ore is first processed, it is purified and most of the uranium is removed. Whatever lead 210 is already present begins to break down, with half of it decaying on average every 22 years. In Roman lead almost all of the lead 210 has already decayed, whereas in lead mined today, it is just beginning to decay."

> Following Trinity test and the rest of nuclear testing campaign, every single living thing or any matter that has been processed in any way has been contaminated and shows high background radiation (compared to pre-Trinity test).

Well, high and high. On average, humans worldwide receive a dose of about 4 mSv/year. Nuclear weapons testing and nuclear accidents contribute about 0.01 mSv/year to that.

Well, "high" was meant in context of the title of the article as in "detectably higher".

Yup, illegal grave robbing in the south pacific is destroying many ships that were lost with hands onboard. https://www.theguardian.com/world/ng-interactive/2017/nov/03...

Obligatory XKCD reference on radiation levels: https://xkcd.com/radiation/

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